Organs Liver (Close Up)
Branch of Hepatic Vein
Hepatic veins are blood vessels which transport the liver’s deoxygenated blood and blood which has been filtered by the liver (this is blood from the pancreas, colon, small intestine, and stomach) to the inferior vena cava. The hepatic veins originate in the liver lobule’s central vein. Hepatic veins are unusual in that they do not have valves. Source
The central vein of the lobules will converge to form two hepatic veins, which will carry blood from the liver to the inferior vena cava. In the middle of each lobule is a central vein and at the periphery of each lobule are branches of the hepatic portal vein and hepatic artery, opening into spaces between hepatic plates. Arterial blood and portal venous blood, containing nutrient molecules absorbed in the gastrointestinal tract mix as the blood flows from the periphery of the lobule to the central vein. Source
The interlobular artery gives off branches called the afferent arteriole, which forms the glomerulus, which is this network of capillaries contained within the glomerular capsule. This is called a Bowman’s capsule or glomerular capsule. The stellate veins join to form the interlobular veins, which pass inward between the rays, receive branches from the plexuses around the convoluted tubules, and, having arrived at the bases of the renal pyramids, join with the venae rectae. The interlobar arteries travel along the bases of the pyramids where they are called the arcuate arteries. The arcuate arteries give off branches that ascend in the cortex called cortical radiate arteries. The afferent arterioles branch off the cortical radiate arteries (a.k.a. interlobular arteries) and bring blood to the glomerulus. Source
The perisinusoidal space (or space of Disse) is a location in the liver between a hepatocyte and a sinusoid. It contains the blood plasma. Microvilli of hepatocytes extend into this space, allowing proteins and other plasma components from the sinusoids to be absorbed by the hepatocytes. Fenestration and discontinuity of the endothelium, as well as its basement membrane, facilitates this transport. This space may be obliterated in liver disease, leading to decreased uptake by hepatocytes of nutrients and wastes such as bilirubin. The perisinusoidal space also contains hepatic stellate cells (also known as cells of Ito), which store fat or fat soluble vitamins including vitamin A. A variety of insults that cause inflammation can result in the cells transforming into myofibroblasts, resulting in collagen production, fibrosis, and cirrhosis.
Sinusoids are low pressure vascular channels that receive blood from terminal branches of the hepatic artery and portal vein at the periphery of lobules and deliver it into central veins. Sinusoids are lined with endothelial cells and flanked by plates of hepatocytes. The sinusoids are lined by two types of cell 1) phagocytic cells called Kupffer cells (macrophages), which phagocytose dead red blood cells, particulate matter, and micro-organisms. 2) sinusoid lining cells which are similar to the endothelial cells that line other blood vessels. Source
Liver Cells Plates
The hepatocytes (epithelial cells of the liver) form branching plates of cells, often only one cell thick, between a system of capillary sinusoids that connect the portal tracts to the central vein. To facilitate the exchange of a wide variety of substances between the blood and hepatocytes,the hepatocytes are directly exposed to the blood passing though the organ, by being in close contact with the liver blood sinusoids. The sinusoids carry blood from the edges of the lobule to the central vein. Source
In neuroscience, stellate cells are any neuron that have a star-like shape formed by dendritic processes radiating from the cell body. The three most common stellate cells are the inhibitory interneurons found within the molecular layer of the cerebellum, excitatory spiny stellate cells and inhibitory a spiny stellate interneurons. Cerebellar stellate cells synapse onto the dendritic arbors of Purkinje cells.
The bile ducts carry bile from the liver and gallbladder through the pancreas to the duodenum, which is a part of the small intestine. Bile is a dark-green or yellowish-brown fluid secreted by the liver to digest fats. After you eat, the gallbladder releases bile to help in digestion and fat absorption. Bile also helps clear the liver of waste products. Source
Branch of Portal Vein
The portal vein supplies approximately 75 percent of blood flow to the liver. The portal vein is not a true vein, which means it does not drain into the heart. Instead, it brings nutrient-rich blood to the liver from the gastrointestinal tract and spleen. Once there, the liver can process the nutrients from the blood and filter out any toxic substances it contains before the blood goes back into general circulation. Abnormally high blood pressure in the portal vein is known as portal hypertension. The condition may cause the growth of new blood vessels that bypass the liver, which can result in the circulation of unfiltered blood throughout the body. Portal hypertension is one of the potential serious complications of liver cirrhosis, which is a condition where normal liver tissue is replaced with scar tissue. The hepatic portal vein is a vessel that moves blood from the spleen and gastrointestinal tract to the liver. Source
The importance of veins cannot be stressed enough. The main function of veins is to deliver blood to the heart. Without veins, our body would not be able to operate. Without veins, there would be no life. Because of this, it is of paramount importance that we protect these vital components of the circulatory system. Before you can protect your veins, you must first become well-informed about the role of veins in the human body, something Summit Skin & Vein Care knows well. veins and arteries. Arteries help transport blood from our hearts to the rest of our body, while the function of veins is to pump blood back into the heart. Veins have a much more complicated job than this simple explanation. While arteries are crucial, gravity’s downward force makes their job of dispersing blood throughout the body much easier. Veins, on the other hand, are faced with the difficult task of delivering blood back to the heart, all while going against gravity. our circulatory system has a two-layer vein anatomy: deep and superficial veins. Superficial veins are comprised in groups of thousands, some so small that they aren’t visible to the eye. Together, these veins work in unison to collect blood from our skin and surrounding superficial tissues. The blood they collect is then moved into our deep veins, which run parallel to our muscles. And Deep Veins, Once blood enters these deep veins, blood is pumped to the heart as these large muscles contract, moving blood along the circulatory system. Healthy veins — deep and superficial alike — have a one-way valve that allows blood to flow upward, toward the heart, but not downward. However, due to genetics and day-to-day health complications, these veins are sometimes unable to function properly. Source
A venule is a small blood vessel in the microcirculation that allows deoxygenated blood to return from capillary beds to larger blood vessels called veins. Venules range from 8 to 100μm in diameter and are formed when capillaries come together. Many venules unite to form a vein. Venule walls have three layers: an inner endothelium composed of squamous endothelial cells that act as a membrane, a middle layer of muscle and elastic tissue, and an outer layer of fibrous connective tissue. The middle layer is poorly developed so that venules have thinner walls than arterioles. Venules are extremely porous so that fluid and blood cells can move easily from the bloodstream through their walls. In contrast to regular venules, high-endothelial venules (HEV) are specialized post-capillary venous swellings. They are characterized by plump endothelial cells as opposed to the usual thinner endothelial cells found in regular venules. HEVs enable lymphocytes (white blood cells) circulating in the blood to directly enter a lymph node by crossing through the HEV. Source
The hepatocytes (epithelial cells of the liver) form branching plates of cells, often only one cell thick, between a system of capillary sinusoids that connect the portal tracts to the central vein. To facilitate the exchange of a wide variety of substances between the blood and hepatocytes, the hepatocytes are directly exposed to the blood passing though the organ, by being in close contact with the liver blood sinusoids. The sinusoids carry blood from the edges of the lobule to the central vein. Source
Kupffer cells (KC) constitute 80-90% of the tissue macrophages present in the body. They reside within the lumen of the liver sinusoids, and are therefore constantly exposed to gut-derived bacteria, microbial debris and bacterial endotoxins, known to activate macrophages. Upon activation KC release various products, including cytokines, prostanoides, nitric oxide and reactive oxygen species. These factors regulate the phenotype of KC themselves, and the phenotypes of neighboring cells, such as hepatocytes, stellate cells, endothelial cells and other immune cells that traffic through the liver. Therefore, KC are intimately involved in the liver’s response to infection, toxins, ischemia, resection and other stresses. The Function of the Kupffer Cells are that the Red blood cells are broken down by phagocytic action, where the hemoglobin molecule is split. The globin chains are re-utilized, while the iron-containing portion, heme, is further broken down into iron, which is re-utilized, and bilirubin, which is conjugated to glucuronic acid within hepatocytes and secreted into the bile. Source
The lymphatic vessels are a part of the human’s circulatory system. They drain the fluid called the lymph from around the cells and carry it through the system of the lymph nodes and lymphatic ducts into the venous blood. Afferent lymphatic vessels drain the lymph from the tissues toward the lymph nodes. Efferent lymphatic vessels leave the lymph nodes and carry the lymph toward the subsequent lymph nodes or toward the lymphatic trunks and ducts and subsequently to the subclavian veins. The deep lymphatic vessels usually follow the course of the arteries and the superficial ones the course of veins. Lymphatic vessels do not drain the bone marrow, cartilage, teeth, epidermis, subcutaneous tissues, nails, hair, splenic pulp, eye sclera, cornea, retina and lens, joint spaces and the spaces between the two layers of the lung membrane (pleura), heart sac (pericardium) and abdominal membrane (peritoneum). It has been long believed that central nervous system does not have lymphatic vessels, but they have been recently discovered in the walls of the sinuses of the dura mater (the hard membrane of the brain). Healthy lymphatic vessels are not visible or palpable on the surface of the body. Inflamed lymphatic vessels can appear as tender red streaks on the inner (medial) sides of the legs or arms or the lateral sides of the neck. The function of the lymphatic vessels are to Return the interstitial fluid and proteins from around the cells in the form of lymph back to the blood. To Deliver the lymph to the lymph nodes, which remove foreign particles, microbes and cancer cells from it. To Transport lymphocytes from one node to another. And to Transport the chyle–a mixture of the lymph and chylomicrons (made of triglycerides, cholesterol and protein absorbed from food in the small intestine)–to the venous blood. Source
This is a thin tube that collects bile secreted by hepatocytes. The bile canaliculi merge and form bile ductules, which eventually become common hepatic duct.